Information on myometrial and fetal adrenocortical activity in non-human primates is important in understanding fetal responses to various stresses and involvement of the fetal hypothalamo- hypophyseal-adrenal axis (HHAA) in initiation of labor. Our Specific Aims Are: I)a) To identify lateral ventricle coordinates in the fetal rhesus monkey brain at 120 d.G.A. to enable placement of laternal venticular catheters (LVC); b) to perform immunocytochemistry for AVP and CRF containing neurons of the fetal rhesus hypothalamus in control and experimental fetuses. II) To determine the roles and interactions of CRF1-41 and AVP in the increased production of fetal androgen in response to instrumentation. We will use specific antagonists to CRF1-41 and AVP administered separately and together to the fetal LVC. III) To determine the roles and interactions of CRF1-41 and AVP in the increased production of fetal ACTH that we hypothesize will occur during fetal hypoxemia. IV) To determine the roles and interactions of CRF1-41 and AVP in the growth of the fetal adrenal cortex and increased fetal plasma androgen concentrations observed prior to parturition. V) To obtain a better understanding of the various factors involved in regulation of the primate myometrium. We will use fetectomized pregnant rhesus monkeys from Ia in which fetuses have been removed but placentas left in situ. We will investigate the role of estrogen in the fetectomized pregnant monkey. We will study regulation of the primate myometrium by uterine stretch, AAM and CAT in vivo. VI) To study the interrelationship of steroids, AAM and CAT in the control of the non-pregnant primate uterus in vivo. Labor is a multifactorial process with interconnected positive and negative feedback loops. Most studies on control of the fetal adrenal, parturition and myometrial function have been performed in sheep. Differences in fetal and maternal endocrinology between primates and sheep dictate that a clear understanding of control of the fetal HHAA in humans awaits firm experimental data in non-human primates.